Tentering chains of this type are disclosed in German Patent Publication DE-OS 1,925,284 (Dornier). These tentering chains are conventionally guided between two guide rails which extend in parallel to each other to form a stretching track. Vertical and horizontal forces are taken up by respective guide rollers. The rollers taking up vertical forces function as carrier rollers, while the rollers taking up horizontal forces function primarily as guide rollers. The guide rollers are mounted for rotation on the journal pins which hingedly interconnect two neighboring links of the tentering chain. Thus, the journal pin performs two functions, it mounts the horizontal guide roller and it hinges the chain links to each other.
Tentering chains of this type carry tenter clamps or hooks for holding the fabric or film of synthetic material. It is known in this connection that the tenter clamp body is constructed as part of a chain link. In such structures a horizontal guide roller is mounted for rotation between two neighboring chain links, more specifically, between the connecting plates of two neighboring chain links, whereby the respective guide roller is rotatably supported by the corresponding journal pin that interconnects the two neighboring chain links forming or comprising portions of respective tentering clamps.
It has been found that in these structures the horizontal guide rollers are exposed to high wear and tear during a film stretching operation because, starting at a certain operational speed, the rotational direction of the guide rollers changes due to the fact that the guide rollers either contact one or the other of the two parallel guide rails. Such a directional reversal of the rotation of the guide rollers is undesirable because it contributes substantially to the wear and tear of these rollers. The higher the speed of the tentering chain, and the lower the tension within the chain, the larger is the range within which the tentering clamp can be caused to oscillate back and forth between the two guide rails which also causes wear and tear on the guide surfaces, not only of the guide rollers themselves, but also of the guide rails.